After seven years of faithful service, my lawn-clipping droid Mowbot has had to be retired... and a replacement is hard to obtain. Rather than face an ever-growing lawn, I've decided it's time to unlock the inventing shed and seek some reader advice.
Robots were supposed to be doing pretty much all our manual labour by this …

COMMENTS

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If spinning blades are a less preffered option may I be the first to suggest fire?

I imagine a systematic flammable liquid spraying system followed by remote ignition and voila your grass is considerably shorter and neighborhood cats are as an added bonus probally going to avoid your garden for a while. Would need to be done less regularly than the conventional method therefore less maintenence.

I like it!

Building on your suggestion...

Add the 'errant youf recognition' capability with the 150 decibel "GET ORF MOI LAWN!" message, connected to fire breathing capacity and flailing blades. World + dog will beat a path to your door (if they can get past the flames).

Fire

Navigation

Equip the thing with a cheap cell-phone camera, use existing software which can locate and read bar codes or QR codes to find the codes stuck on a few things round the garden. Then triangulate off these. Should give you very accurate positioning.

Sonar navigation

The buried wire is an elegant method, but it does incur some sweat equity, and after all, isn't that what we're evading here? The idea of using a mower-mounted camera an QR signposts is a great alternative that allows one to program alternate mowing patterns to avoid embedded streaks.

But it also requires some sophisticated optics, and could get foiled by obstructions such as trees.

I'd propose another alternative navigation system which retains the programming flexibility of the QR code / camera scheme, and that would involve planting ultrasonic transponders around the yard, and triangulating based on the time delay from the mower's interrogation "beep" to the receipt time of the transponders' response beeps. The slower acoustic propagation velocity will allow for high-precision location determination without requiring nanosec timing measurements.

Beacons could be identified by unique ultrasonic frequencies, and use of parallel -channel DSP could be applied to time-of-arrival determination. And the physical layer hardware would be trivial to implement. Beacons would require little power, and could run indefinitely given small solar panels.

Also...

Will it have a container for the clippings and, if so, then, when the container is full, can you get it to locate the compost bin (even if I have to stick one of Chistoph's QR codes to it), climb up it, remove the lid (optional, I may possibly be capable to remembering to do this before starting the mower) and deposit said clippings in the bin before carrying on where it left off?

"I've decided it's time to unlock the inventing shed and seek some reader advice."

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Is Mr. Travaglia unavailable, down under in Aotearoa or some similar place with more vowels than is healthy? He obviously has more devious mind than your average El Reg reader, and if I ever wanted to build a killer robot I'd contact him immediately.

Surely you could strap a mower to the front of Stephen Hawking's wheelchair. That would have enough power and weight to push stuff around, and it's covered in tech, so presumably it could be controlled remotely?

BTW I'm not condoning the hijacking of the Prof himself, but what the hey, he's not got anything better to do, and he could do any work remotely over the Wifi link while trundling around the lawn.

GAOT? That acronym

@Kevin Johnston

Still, they're to be preferred over sheep. Goats clip the grass (provided they can be arsed to do so in the first place); sheep rip out the grass, roots and all. They're the bane of the still-arable regions around the Sahara

@Stoneshop

You've got that the wrong way round mate. It's goats that rip the grass out by the roots, whereas sheep only crop the grass. I know because every couple of years or so we go out feral goat shooting up at my mate's farm because the bastards destroy the sheep paddocks, and it sure as hell ain't the sheep that do the damage. In fact even the roos do more damage than the sheep!

At the Gorge Wildlife Park near Adelaide, there's an even more vivid example: a series of small paddocks or large enclosures, each containing a few specimens of one type of animal. The one with the goats has been eroded down to more than a foot below ground level across *every square inch* of the enclosure. No other animal does this so destructively.

@Steven Roper

KISS

It sounds like you have already nailed the First of Larry Wall's Three Great Virtues of a Programmer (i.e. Laziness, for the truly lazy the other two are Impatience and Hubris - give yourself a a pat on the back for not bothering to look them up).

Impatience should require the use of Off the Shelf parts - possibly an ideal opportunity to buy a Raspberry Pi if/when they ever become available.

However, going back to Laziness for a minute. I don;' feel that having the device controllable from a phone or PC quite does it, for the truly lazy. Surely the object of complete laziness is for the device to do everything itself? Possibly up to and including re-ordering it's own SLA batteries when it detects the current ones are failing (shades of 2010 A Space Odyssey:, perhaps? Just keep it away from hard vacuum.).

One final point on the topic of a cylindrical cutter. Check out the blades that woodworkers use in planer/thicknessers. Apart from being scary sharp, really: SCARY sharp, they could be the sort of thing you'd be looking for. With a few adaptations, the Mk2 might even keep your hedges in trim.

spinning blades are so imprecise

no matter how sharp your stanley blades are, and how fast or slow your spinning plank of wood, you'll never get all the grass at the same height.

So I suggest the use of lasers and small mirrors from the outside of a disco mirror-ball. position the mirrors all around the circumference of your lawn (reflective side inwards). Then set up one of those military spec lasers at the desired height on the top of a spinning lawn waterer gizmo. Switch on the spinning, switch on the laser, and presto, uniformly cut lawn. just make sure the lawn is empty before you begin the process, no responsibility will be accepts for any cats missing their paws below the kneecaps.

Clippings

Emptying into a compost heap seems like it could get complicated, but how about interchangeable hoppers so it could simply drop one off when its full and pick up another, leaving the owner to empty the hoppers. These coud be combined into a drive through charging dock/kennel.

Idea's

Proximity sensors (Laser against fence all 4 directions) and a pre-programmed layout would give exact position at all times, as long as you tell it never to go out of area, then proxmity sensors on bottom to stop it from hitting things. Set it all up on a RasberryPi with that being the controller. you know I might have a crack at this myself converting an electric one and using an upside down L shaped pole in corner to stop cable snagging.